Outdoor furnaces can heat your home efficiently. Firewood is cheaper than natural gas or oil, and wood is a natural resource that can be replenished. As its name implies, outdoor furnaces are designed to be placed outside the house and supplement your home's existing source of heat, thus lowering your heating costs. When choosing an outdoor furnace, it's important to choose the right size.[source: Service Magic]

 

Follow these steps to learn how to install an outdoor furnace.

  1. Make a concrete pad large enough to hold your furnace, with room for you to stand when loading the furnace. Make sure the pad is at least 4 inches (10.16 centimeters) deep. (You will have to make a mold to pour the concrete in.)
  2. Dig a trench below the frost line from the furnace to the house, with a backhoe. The trench will prevent heat loss or freezing of the pipe, since the ground will be between 45 and 55 degrees Fahrenheit (7 and 13 degrees Celsius).
  3. Place the furnace on the concrete pad.
  4. Measure the distance from the house to the furnace. Take a PEX pipe (i.e. hot water pipe) of that length and put it in the trench. Place the same length 12/3 110V wire in the same length 4x6 PVC pipe. Put the PVC pipe into the trench too.
  5. Mount a heat exchanger in the outlet plenum (ventilator) of the furnace. You should be able to buy one that fits your plenum. The heat exchanger should easily slide into the plenum. You can fasten it in place with an L -shaped bracket.
  6. Connect one end of the PEX pipe to the furnace, and the heat exchanger to the hot water heater. Use another run of pipe and a pump to fasten the other end of the PEX pipe to the hot water heater.
  7. Put the circuit breaker into the breaker box. Attach the 110V wire to the circuit breaker and the furnace. Install and connect the thermostat.
  8. Fill the furnace with water. Start the fire.[source: Outdoor Wood Furnaces]